Available online 17 October 2022, 105322

Comparative evaluation of antibody screening tests after SARS-CoV-2 infection or vaccination

Excellent test performance in very young and very old subjects (6 to 99 years)

Parallel occurrence of N-specific antibodies with nABs in recovered subjects

Positive Viramed-Test results correspond with T-cell reactivity

Viramed-Test is suitable for differential diagnosis of SARS-CoV-2 infection and/or vaccination

: Detection of seroconversion after SARS-CoV-2-infection or vaccination is relevant to discover subclinical cases and recognize patients with a possible immunity.

: Test performance, effects of age, time-point of seroconversion and immune status regarding neutralizing antibodies (NAbs) and T-cell-reactivity were investigated.

: Two antibody assays (Viramed-Test for S/N-specific IgG, Roche-Test for N-specific IgA, -M, -G) were evaluated with classified samples. In total, 381 subjects aged 6-99 years, who had either recovered from the disease or had been vaccinated, were screened for SARS-CoV-2-specific antibodies. This screening was part of an open observational study with working adults. Additionally, children and adults were analyzed in a longitudinal COVID-19 study in schools. For immunity evaluation, virus neutralization tests and ELISpot tests were performed in a subgroup of subjects.

: Viramed revealed a slightly lower test performance than Roche, but test quality was equally well in samples from very young or very old donors. The time-point of seroconversion after the respective immunization detected by the two tests was not significantly different. N-specific antibodies, detected with Roche, highly correlated with NAbs in recovered subjects, whereas a positive Viramed-Test result was paralleled by a positive ELISpot result.

: Viramed-Test was not as sensitive as Roche-Test, but highly specific and beneficial to distinguish between recovered and vaccinated status. For both tests correlations with humoral and cellular immunity were found. Of note, the expected early detection of IgA and IgM by the Roche-Test did not prove to be an advantage over IgG testing by Viramed.

SARS-CoV-2-specific antibodies

seroconversion

test performance

neutralizing antibodies

T-cell-reactivity

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